Motor Load Damping Factor
Motor Load Damping Factor
(OP)
Can someone please explain load damping factor as it relates to electric motors?
What information is required to calculate the load damping factor?
What information is required to calculate the load damping factor?





RE: Motor Load Damping Factor
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(2B)+(2B)' ?
RE: Motor Load Damping Factor
RE: Motor Load Damping Factor
So I dug out from the crates in the corner of my garage my old course notes from Power System Stability with Professor Begovic at Georgia Tech. For induction motor with frequency fe applied he draws motor torque speed curve and load curve similar to a centrifugal pump. He computes the mechanical power at the operating point and calls it Pm.
Then he shifts the electrical frequency fe up a little bit to fe' which creates new torque speed curve and new operating point with corresponding power Pm'.
He defines D = dP/df = (Pm' - Pm) / (fe' - fe)
There are also ways to compute D for other loads besides motors. Somehow they are rolled into a composite D.
The use of this D in the power system swing equation which is shown on upper right corner of page 5 attached (article by Begovic that I found thru google)
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(2B)+(2B)' ?
RE: Motor Load Damping Factor
Hopefully you can see that in the swing equation matches a simple SDOF system:
position x <-> angle delta
force F < - > power P
damping c = F/(dx/dt) <-> D = P / [d/dt(delta)] <-> P / w
or linearized as dP / dw
There may be a factor of 2*pi missing somewhere
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(2B)+(2B)' ?
RE: Motor Load Damping Factor
It doesn't seem like the damping factor is something that I can calculate with the information I have. I am doing a stability study with some large induction motors, and I only have their nameplate data. Perhaps the manufacturer can provide the damping factor of each motor?
RE: Motor Load Damping Factor
RE: Motor Load Damping Factor
The loads of the motors I am working with are screw compressors. Any ideas of what the damping factor of a screw compressor is?
In the model I'm using, the damping factor exists in the Load Torque equation:
Tload = Tnom*(1 + delta_w)^D
where:
delta_w is the motor speed deviation from nominal (per unit slip)
Tnom is the motor load torque at synchronous speed
D is the damping factor